Question: $ { \left[\begin{array}{rr}{2} & {-1} \\ {-1} & {-1} \\ {4} & {1}\end{array}\right]+\left[\begin{array}{rr}{-1} & {0} \\ {-2} & {-1} \\ {-2} & {3}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}+{-1} & {-1}+{0} \\ {-1}+{-2} & {-1}+{-1} \\ {4}+{-2} & {1}+{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{1} & {-1} \\ {-3} & {-2} \\ {2} & {4}\end{array}\right]}$